Electromotor



June 20, 1933.

R. GOLD Er L ELECTROIOTOR onginal Filed June 25, 1929 Patented June 20, 1933 UNITED STATES PATENT OFFICE mc'rnoxo'roa .Original application led June 25, 1929, Serial No. 373,588, and in Austria July 16, 1828. Divided and y this application Med July 3, 1980. Serial lo. 465,569.

Our invention relates to improvements in electric motors.

This application is a division of U. S. atent application Serial No. 373,588, filed une 6 25, 1929, and disclosing the same generic invention.

Efforts have already been made, by various ways and means, to solve the problem of constructing electric motors which are to serve, for instance, for driving pumps, in such way that they can operate direct in the water or other liquid to be raised without having to fear break-downs. It .has been suggested for instanceto insert a .fluid tight partion in the form of a thin walled tube in the space between the stator and rotor of the electric motor (particularly in the case of threcphase motors with squirrel-cage rotors), which tube closes tightly around the casing of the stator, so that the winding of the stator is then completely closed in. The hollow space of circular annular section containing the stator was to be filled with an insulating oil, and as the rotor can be so produced as to be'unafected by water or other fluids,

. such a motor can be plunged into the liquid which is to be delivered by the pumpdriven by the motor straight away.

New the object of the present invention is to make the partition between rotor and stator as thin as possible in order that quite a narrow space between rotor and stator shall suffice to take this partition, thus enabling the dimensions of the parts of the motor coming into question to be reduced as far as possible.

The tube inserted in the space between rol tor and stator may consist of a suitable metal, o or metal alloy produced with a thickness of wall being only a small fraction of a millimeter. Of course, a tube with such thin walls is easily deformed, and means must be provided to prevent such deformation if the cer- 45 tainty of operation of the electric motor is to be maintained; the rotor. must be prevented from cominginto contact with the thin plate tube, as in such case it would soon be destroyed,`which would consequently in turn destroy the sealing of the stator chamber, in

which is to be found the winding connected with the system. l

The thin partition tube is subjected, on the chamber and contents thereof, including the substance filling the hollow space can expand as freely as possible under the influence of the heat generated in operation, or that the expan'sions caused by the heat of all these parts 1s so small that practically they need not be taken into consideration. These two main vpossibilities; can also be simultaneously turned to account with one another.

Care must also be taken to see that the thin partition-tube which seals the stator chamer from the rotor is less susceptible to compressive stresses which emanate from the space in which the rotor operates than to compressive stresses which emanate from the interior .of the stator chamber. Every tube is, ofcourse, more easily able to take up internal pressure than external pressure, as the Wall of such a tube is mainly under tensile stress from the internal pressure, while any pressure takingfeifect from the outside tends to cause the wall of the tube to collapse inwards. In the case .of an extremely thin walled tube as is to be used here, this difference in the capacity for withstanding internaland external pressure is naturally emphasized.

It will be seen from this that care must be taken to avoid high pressure taking eiect on the thin-walled tubular partition from the stator chamber and that if the difference between this pressure and the vhydrostatic pressure taking eect from the other side'is 4able to deform the tube towards the rotor,

it will necessarily uickly be destroyed as a consequence-of the riction ofthe rotor.

regulate the pressure t ereo in any desiredy manner. l

In order that our invention may be the better understood, we will now proceed to describe the same in` relation to the accomanying drawing, reference being had to the etters and res marked thereon; like let- 15 ters refer to 'ke parts in the various figures in which Y Fig. 1 is an axial section through a motor constructed according to our invention;

Fig. 2 a cross section through the rotor of the said motor drawn on an enlarged scale and taken cn the line B-B of Figure 1;

Fig. 3 shows means for t' htly fixing the ends of the thin-walled tubiar partition;

Fig. 4 is an axial section of a modification of the motor with parts broken away;

Fig. 5 is an axial section of a further modificition of the motor with parts broken away; an

Fig. 6 shows a modification of Fig. 4, wherein an open pi e is connected up with the expansion cham r.

The rotor 1 is carried on the shaft 2, which ishousedinthehearingsand of the casing 5. This housin 5 also encloses the stator 6 with its win 'ngs 7 and consists in this case of a tubular part and end pieces 8 and 9, the end piece 9 being closed by a cover 10 containin the bearing 4. The end ieces8 and 9 have anges il and 12 respectivel a thinwalled partition tube 13 being tight y mounted in the inner periphery thereof. By this ineens a chamber of circular annular section, ciosed on ai! sides, is formed inside the casing 5 by the two iianges 11 and 12 and the thinwalled partition tube 13, inside which chamber the stator with its windings is enclosed. The current conducting cable 14 of the stator can be passed through in a perfectly tight and simpie manner at any oint of the casing. The end pieces 8 and 9 o the housing may he provided with a rtures 15 and 16, respectiveiy', through w ich water can netrate from outside into the room of t e rotor.-

These apertures 15 and 16 also may be provided with iiiters or may be entirely omitted.

Fig. 3 shows the manner in which the thinwaiied partition tube 13 is ti htly closed to the stator casing. Each en of the cylindrical wall 13 is provided with a flange 18 which is placed a' ainst the anges 11 and 12, respectively, of tige rmotor casing 5 and fixed thereto by the pressure ring 19.

ln accordance with our invention the stator chamber is filled with gaseous substances. As a gaseous iilling substance even air may -of a non-injurious nature, may e naturaII introduce If the motor is to operate at only a slight depth in a liquid, the hydrostatic pressure takin effect on the thin tubular partition will o be comparatively low, so that the partition tube is easily able to take this pressure. It is however often necessary to provide yfor greater alterations in volume in the interior of the stator chamber, which alterations are due to the expansion of the gaseous filling substance as a consequence of the heatin in workin o long as t e be used, .or alternatively any ressure arising hereby in the interior of t e stator chamber is not f greater than the h drostatic pressure of the surrounding liqui takin effect from the other side on the thin-wal ed partition tube, no risk will exist of an undue stress being put upon the tubular partition. If, however, an excess of pressure arises in the interior of the stator chamber beyond the hydrostatic pressure, the thin part1tion-tube may very easily be pressed in and the consequence of this would be that the rotor would rub on the tubular partition and grind through the latter in a short time.

Now in order to prevent an such increase in pressure in the stator cham r, devices can be provided which ensure an automatic regulation of the pressure inside the stator chamber.

It may for instance be advisable to connect up with the stator chamber gas-filled expansion vessels, which may have rigid walls and which only fulfil thel purpose of placing greater space at disposal for the filling medium contained in the stator chamber, so that the increasing pressure in the interior of the stator chamber as a consequence of the expansion of the filling medium by heat cannot rise to'an inadmissable degree. Such gasfilled expansion chambers with rigid walls render a compensation of pressure possible in a simple manner.

Such expansion chambers can be arranged either inside or outside the motor casing or an enlargement of the motor casing itself may fulfil this object.

ig. 4 shows by way of example a vertical arrangement, wherein an expansion vessel 21 with rigid walls is placed outside the motor Casin 5 and communicates with the stator cham r 22 by means of the pipe 20. The gaseous iillin medium fills up the stator chamber 22, t e pipe 20 and the interior of the expansion vessel 21.

In Fig. 5 an enlargement of the motor casing 5 itself serves as expansion chamber, the room 38 fulfilling the object of the expansion vessel 21 shown in Fig. 4.

Itis also possible as illustrated by Fig. 6,10 connect up with the stator chamber 22 an open pipe 23 emer in from the surface of the external liquif ne or more enlargelll , sure either does not exceed the hydrostatic expansion `from heat occurrlig pressure of the external liquid or not beyond defined limits.

The use of a pressure below that of the atmos here can also be combined with the use of gas-filled expansion chambers as described above, which renders it possible to make the dimensions of these expansion chambers ver small. By choosing a preur'e sutlicient y below that of the atmosphere, such expansion chambers are naturally not necessary at all.

Any such pressure below that of the atmosphere in the interior of the stator chamber naturally also carries with it the consequence that the walling of the thin partition-tube. is kept continually pressed tightlfy to the stator plate supporting it which is o great advantage as in this case the thin partition tube is secured against any contact with the rotor.

The gas filler must not fill up the entire stator chamber in any case. Sometimes it will be advantageous to fill lthis chamber art- 1y with a gas and partly with a liquid, w ereby it is obtained that the liquid filler can freely expand under the influence of heat into the space kept by the s filler.

If the motor is intend to be plunged to any considerable depth, the hydrostatic ressure of the duid surrounding it may ge so great as to prevent the thin-walled partition tube withstanding itwithout counter-pressure from the interior of the stator chamber. Care is therefore to be taken that as'- rfect a compensation of ressure as possi le on both sides of the walling of the partition-tube is obtained, in which connectionit is naturalalso necessary to take into consideration l the variability ofthe pressure in the interiorl of the stator chamber as a consequence of the y during operation. All the means descr abovev may be used for the regulation of pressure in the in-` terior of the stator chamber. A

The motors designed according to our invention may be used for the direct drive of pumps vplunged into water, into crude oil (oil wells) lor such like can be arranged both with VY vertical-and horizontal shafts.

Having now particularly described and ascertained the nature of our said invention and in what manner the same 1s to be performed, we declare that what we claim is 1. An electric motor ada ted to be used under water or other liqui com rising a rotor, a stator, a casing surroun 'ng said stator, an 1m Vrforate metallic partition-.-

tube, thinner t an one millimeter, arranged in the airgap between said stator and rotor and forming with said casing a liquid-ti ht stator chamber of substantially ann ar cross-section, and a gaseous filling medium in said stator chamber.

2. An electric motor adapted to be used under water or other liquid, com rising a rotor, a stator, a casing surroun ing said stator, an. imperforate metallic partition tube, thinner t an one millimeter, arranged in the air gap between said' stator and rotor and forming with said casing a liquid-ti ht stator chamber of substantially ann ar cross-section, and a gaseous filling medium in said stator chamber, the gas pressure therein, even at the maximum temperaturerise of the'A motor, being suiciently low to prevent the said partit1on-tube from beingv a degree that no risk exists of the thin par- .titio'n-tube being pressed in.

4; An electric motor adapted to be used under water or other liquid, comprising a rotor, a stator, a casing surroundin said stator,

an imperforate metallic partition-tube, thinner than one millimeter, arranged in the air gap between said stator and rotor and formlng with said casing a liquid-tight stator chamber of substantlally annular cross-section, and a gaseous illmg medium in said stator chamber, the gas pressure therein even at the maximum temperature-rise, being always lower than the pressure outside the lo 5. An electric motor as set forth in Claim said partition-tube.

1, having at least one expansion chamber of ksuitable size, which is provided with rigid walls, filled with a gaseous medium, and communicatin with the said stator chamber.

6. An e ectric motor ada ted to be used under water or other liqui com rising a rotor, a stator, a casing surroun ing said stator, an imperforate metallic partition tube, thinner t an one millimeter, arranged in the air ga between said stator and rotor and forming with 'said casing a liquidtight stator chamber of substantially annular cross-section, a gaseous filling medium in said stator chamber, and at least one exansion. chamber formed as an integral'ena ment of the motor casing itself, filled wit a gaseous medium, and communicating with the said stator chamber. g

7. A nelectric motor adaptedtobeused under water orothor liquid, comprising a rotor, a stator, a casing surrounding said stator, an imperforate metallic partition-tuba, thinner than one millimeter, arranged in the air gap 5 between said stator and rotor and-forming with said casing a liquid-tight stator chamber of substantiall annular cross-section, a gaseous medium in artly said stator Y chamber, and a liquid metthe remaining 10 part of the said stator cham t 1n testimony whereof we amx our signaures.

RICHARD GOLD. JULIUS 

